Liquid crystal display device

ABSTRACT

A liquid crystal lens is provided on a liquid crystal display panel. Electrodes extending vertically to a plane of drawing are provided on an upper substrate of the liquid crystal lens at predetermined intervals. No electrodes are provided on a lower substrate. An initial alignment of liquid crystal molecules in the liquid crystal lens is vertically directed with respect to the plane of the drawing. A voltage applied to the upper substrate electrodes generates a transverse electric field to rotate the liquid crystal molecules. Polarization light emitted from the liquid crystal display panel is vertically directed to the plane of the drawing, which generates a refractive index distribution of the polarization light in a liquid crystal layer to form a convex lens within the liquid crystal lens. This lens allows first and second pixels to be recognized by right and left eyes to allow a three-dimensional display.

CLAIM OF PRIORITY

The present application claims priority from Japanese Patent ApplicationJP 2011-063331 filed on Mar. 22, 2011, the content of which is herebyincorporated by reference into this application.

TECHNICAL FIELD Background

The present invention relates to a display device, and moreparticularly, to a liquid crystal display device which allows athree-dimensional display using a liquid crystal lens.

A liquid crystal display panel includes a TFT substrate having pixelelectrodes and thin film transistors (TFT) arranged in a matrix, and acounter substrate that is located opposite the TFT substrate, havingcolor filters positioned corresponding to the pixel electrodes on theTFT substrate. A liquid crystal is interposed between the TFT substrateand the counter substrate to form a display region. An image is formedby controlling light transmittance through liquid crystal molecules foreach pixel. Since the liquid crystal is capable of controlling onlypolarization light, a light ray from a backlight is polarized by a lowerpolarizer before incidence to the TFT substrate, and controlled by aliquid crystal layer. It is further polarized by an upper polarizeragain so as to be emitted to the outside. So the light emitted from theliquid crystal display panel is polarization light.

Various methods for forming a three-dimensional image on the liquidcrystal display panel have been proposed. Among all of those methods,one which provides the liquid crystal lens on the liquid crystal displaypanel has been focused on its application especially to a small-sizeddisplay device because of features that no special glasses are requiredfor visual recognition of the three-dimensional image, and thatselection between the two-dimensional image and the three-dimensionalimage may be performed.

Japanese Patent No. 2862462 discloses the structure in which a liquidcrystal lens has liquid crystal molecules interposed between an uppersubstrate and a lower substrate, upper substrate electrode patterns areformed in stripes on the upper substrate, and flat solid lower substrateelectrode patterns are formed on a lower substrate so that the lens isformed through alignment of the liquid crystal molecules along theelectric field generated by applying voltage to both the upper and thelower substrate electrode patterns.

Japanese Unexamined Patent Application Publication No. 2009-520231discloses a liquid crystal lens that uses an electric field generated bya longitudinal electric field between the upper substrate electrodepattern and the lower substrate electrode pattern. Those upper and thelower substrate electrode patterns on the upper and the lower substratesare similar, but they are rotated to form an angle of 90° with eachother. This makes it possible to direct the lens to rotate at 90°through the method of applying the voltage to the upper and the lowersubstrate electrode patterns. In the case where a display screen is inboth horizontal and vertical modes, the three-dimensional display may beperformed.

FIGS. 11 and 12 schematically show a liquid crystal lens 10 and a 3Ddisplay using the liquid crystal lens 10. The terms 2D display and 3Ddisplay herein refer to the two-dimensional display and thethree-dimensional display. The liquid crystal lens 10 has the samestructure as the liquid crystal display element configured to interposea liquid crystal between two substrates each with an electrode. However,it is not intended to be used for the control of polarization directionlike the liquid crystal display, and accordingly, no polarizer is used.

FIG. 11 schematically shows the electrodes formed on the two substratesthat interpose the liquid crystal. The electrode on the lower substrate30 has a laterally long rectangular pattern as indicated by a solidline, and the electrode on the upper substrate 20 has a rectangularpattern as indicated by a dashed line. Rectangular boxes A and B denoteelectrode terminals that externally apply the voltage. The line whichconnects the electrode terminal with the electrode on the aforementionedsubstrate denotes a wiring. The electrode connected to the electrodeterminal A may be designated as an electrode A, and the electrodeconnected to the electrode terminal B may be designated as an electrodeB. Basically, each pattern of the upper and the lower substrates is notlimited, and those patterns may be reversed with respect to the upperand the lower substrates. Transmission of light is required, andaccordingly, the transparent electrode such as ITO is used for formingat least the electrode as shown by the dashed line, which covers theentire display portion.

Arrow P shown in FIG. 11 denotes a rubbing direction on the upper andthe lower substrates. The liquid crystal interposed between thosesubstrates is aligned to have a part at a longer axis side directedtoward the arrow direction when the voltage is not applied. FIG. 12 is asectional view taken along line Y-Y of FIG. 11. The electrode at theside of the lower substrate 30 is set so that two pixels in the LCDbelow the liquid crystal lens 10 are arranged between two electrodes.Actually, a pitch of the two pixels is not the same as that of theelectrodes. Those pitches are appropriately designed in accordance withan assumed viewing position.

FIG. 12 illustrates a state where each voltage applied to the upper andthe lower electrodes is set to be the same, that is, the voltage is notapplied to the liquid crystal. In other words, the liquid crystal lens10 is in an off-state. In this state, the liquid crystal is entirely inan alignment direction regulated through rubbing. The liquid crystallens 10 as an optically uniform medium with respect to the transmittedlight does not act so as to directly output the 2D image on the LCD fordisplay.

FIG. 13 illustrates a state where the voltage is applied to the upperand lower electrodes of the liquid crystal lens 10 so as to change thealignment direction of the liquid crystal, that is, the liquid crystallens 10 is in an on-state. Like the LCD, in a normal state, an ACvoltage is applied for preventing deterioration in the liquid crystal.The electrode on the upper substrate 20 is solid, and the lowerelectrode locally exists. Therefore, the electric field applied to theliquid crystal is not uniform in the longitudinal and lateraldirections. Along the radial (parabolic) electric field toward the uppersolid electrode from the lower locally positioned electrode, the liquidcrystal molecules are also radially aligned as shown in the drawing.

A liquid crystal molecule 50 exhibits a birefringent property. Thecomponent in the longitudinal direction (longer axis direction) of themolecule of polarization light of a transmitted beam is brought intoextraordinary light with a high refractive index. The componentperpendicular to the one in the longitudinal direction of the moleculeis brought into ordinary light with a lower refractive index than thatof the extraordinary light. The intervening angle may be obtained byresolving the component into the extraordinary light component and theordinary light component in the same manner as vector resolution. Thebirefringent property refracts incident light to the lower substrate 30as shown in FIG. 13. In other words, the liquid crystal lens 10 shown inFIG. 13 provides the optical property similar to that of the convexlens.

The polarizing direction 40 of the incident light, that is, the lightemitted from a liquid crystal display panel 100 is substantially inparallel with the rubbing direction on the liquid crystal lens 10, theratio between the portion with a high refractive index (extraordinarylight) and the portion with a low refractive index upon passage of theincident light through the liquid crystal lens 10 varies by location. AsFIGS. 11 and 12 show, the longer axis direction of the liquid crystalmolecule 50 is consistent with the rubbing direction which determines aninitial alignment of the liquid crystal.

Referring to FIG. 13, a dashed line representative of an interface of aconvex lens 11 schematically shows the interface between the portionwith a high refractive index and the portion with a low refractiveindex. The same effect as the one derived from the convex lens isobtained in the liquid crystal. When two pixels in the liquid crystaldisplay panel 100 are provided under the effect of the convex lens asshown in FIG. 13, light rays from a first pixel 200 change the pathsmainly to the right side, and light rays from a second pixel 300 changethe paths mainly to the left side. Referring to FIG. 13, each of codes“r”, “g” and “b” of the first pixel 200 and the second pixel 300 denotesa “red sub-pixel”, a “green sub-pixel” and a “blue sub-pixel”,respectively, common to all the pixels. In the condition where theliquid crystal lens 10 and the liquid crystal display panel 100 areappropriately designed so that signals for a right eye and a left eyeare displayed on the first pixel 200 and the second pixel 300, the lightfrom the first pixel 200 and the light from the second pixel 300 may beguided to the right eye and the left eye of an observer, respectively.This allows the observer to recognize the 3D image.

Meanwhile, on demand from recent use of the liquid crystal displaydevice, the function capable of selectively displaying in the portraitmode (vertical display) and the landscape mode (horizontal display) hasbeen added like a mobile phone. To cope with the demands from the usage,the 3D panel is required to have the function for selecting the displaybetween the vertical and the horizontal modes. FIG. 14 shows an exampleof generally employed art which allows the liquid crystal lens 10 toselectively display in the vertical and the horizontal modes.

Like the case in FIG. 11, the solid line indicates lower substrateelectrode patterns 31, and the dashed line indicates upper substrateelectrode patterns 21. Each of the upper substrate 20 and the lowersubstrate 30 is formed of thin electrodes each as the local electrodeand thick electrodes so as to be solid corresponding to the thinelectrodes on the counter substrate. Codes “A”, “B”, “C” and “D” referto the terminal electrodes for application of the voltage to therespective electrode patterns, and corresponding electrodes as well.

FIGS. 15 and 16 show sectional views each showing a state where thelaterally extending cylindrical liquid crystal lens 10 as shown in FIG.14 is formed. The consequence substantially the same as the onedescribed referring to FIGS. 12 and 13 occurs so as to provide thefunction of the liquid crystal lens 10. The state shown in FIGS. 15 and16 is different from the one shown in FIGS. 12 and 13 in that atransverse electric field is generated between the electrodes A and C asindicated by FIG. 16. This transverse electric field is directedsubstantially in the same direction as the rubbing direction, thusgiving no fatal impact on the liquid crystal alignment and the lenseffect.

FIGS. 17 and 18 are sectional views each taken along line X-X of FIG.14. FIG. 17 shows the state where the voltage is not applied to theliquid crystal for 2D display. The liquid crystal molecules 50 eachdrawn as a circle in the drawing represents that the longer axis islongitudinally directed with respect to the upper electrode, that is, inthe vertical direction with respect to a plane of the drawing. FIG. 18shows the state where the voltage is applied so that the electric fieldis generated between the electrode B and the other electrodes A, C and Don the upper substrate 20. Like FIG. 13 or FIG. 16, the liquid crystalis aligned again along the radial electric field directed toward C fromB so as to form a downward convex lens shape. The transverse electricfield is simultaneously generated between the electrodes B and D on theupper substrate 20. The liquid crystal is also aligned again along thiselectric field.

SUMMARY OF THE INVENTION

In the course of observation that the transverse electric field not onlydisarranges the shape of the liquid crystal lens 10 but also causes thelens effect to disappear over a long time (owing to change in the liquidcrystal domain) as experimental results, it is found to be difficult toput the above-described mode into practical use for selection of thedisplay between the vertical and horizontal modes. The present inventionprovides a liquid crystal lens 10 applicable to various display modesincluding selection of the display between the vertical and horizontalmodes.

Firstly, a liquid crystal lens is provided on a liquid crystal displaypanel provided with a first pixel and a second pixel. The liquid crystallens is formed by interposing the liquid crystal between a firstsubstrate and a second substrate. Electrodes in stripes are formed onthe first substrate of the liquid crystal lens, which extend in a firstdirection, and are arranged in a second direction orthogonal to thefirst direction. No electrodes opposite those formed on the firstsubstrate are formed on the second substrate.

The initial alignment of the liquid crystal is set to be in the samedirection as that of the electrodes in stripes formed on the firstsubstrate. The polarizing direction of the polarization light emittedfrom the liquid crystal display panel is set to be the same as that ofthe electrodes in stripes formed on the first substrate. Uponapplication of the voltage between electrodes in stripes formed on thefirst substrate, the transverse electric field is generated, along whichthe liquid crystal is rotated for alignment again. This may allowformation of the convex lens in the liquid crystal lens. The convex lensforms the three-dimensional image while allowing the first pixel to berecognized by the right eye and the second pixel to be recognized by theleft eye.

Secondly, the liquid crystal display device is configured to allowselection of the display screen between a vertical mode and a horizontalmode. When electing the display screen in the horizontal mode, thegenerally employed liquid crystal lens of longitudinal electric fieldtype is used. When selecting the display screen in the vertical mode,the liquid crystal lens of the transverse electric field type is used.This makes it possible to realize the three-dimensional liquid crystaldisplay device using the liquid crystal lens, capable of selecting thedisplay screen between the vertical mode and the horizontal mode.Conversely, the liquid crystal lens of transverse electric field typemay be used for selecting the display screen in the horizontal mode, andthe liquid crystal lens of longitudinal electric field type may be usedfor selecting the display screen in the vertical mode.

According to the present invention, the transverse electric field may beused as the liquid crystal lens, thus expanding the application of theliquid crystal lens of the liquid crystal display device. This makes itpossible to realize the three-dimensional display using the liquidcrystal lens in the liquid crystal display device capable of selectingthe display screen between the vertical mode and the horizontal mode.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a sectional view representing a three-dimensional displayusing a liquid crystal lens of transverse electric field type;

FIG. 2 is a plan view of an upper substrate of the liquid crystal lensshown in FIG. 1;

FIG. 3 is a schematic view showing a relationship between an initialalignment direction of a liquid crystal molecule and the polarizationlight;

FIG. 4 is a schematic view showing a diagonal passage of thepolarization light through the liquid crystal molecule;

FIG. 5 is a schematic view showing a relationship between the liquidcrystal molecule and the polarization light when a sufficiently hightransverse electric field is applied to the liquid crystal molecule;

FIG. 6 is a plan view showing a pixel structure in a liquid crystaldisplay panel;

FIG. 7 is a plan view showing an arrangement of electrodes of the liquidcrystal lens according to Example 2;

FIG. 8 is a sectional view showing the liquid crystal lens using alongitudinal electric field according to Example 2;

FIG. 9 is a sectional view showing a state where the liquid crystaldisplay device is used as a two-dimensional display device withoutapplying the voltage between the electrodes according to Example 2;

FIG. 10 is a sectional view of the liquid crystal display deviceaccording to Example 2, which forms a convex lens using the transverseelectric field for three-dimensional display;

FIG. 11 is a plan view showing an arrangement of electrodes of theliquid crystal lens in a three-dimensional liquid crystal display deviceof longitudinal electric field type;

FIG. 12 represents an example of usage as a two-dimensional displaydevice without forming a lens in the liquid crystal lens;

FIG. 13 is a sectional view representing formation of the convex lens inthe liquid crystal lens using the longitudinal electric field;

FIG. 14 is a plan view showing an arrangement of electrodes of theliquid crystal lens as related art so as to select a display screenbetween a vertical mode and a horizontal mode;

FIG. 15 is a sectional view of the liquid crystal display device shownin FIG. 14 when the vertical mode is selected, and the two-dimensionaldisplay is performed without applying the voltage to the respectiveelectrodes;

FIG. 16 is a sectional view of the liquid crystal display device shownin FIG. 14 when the vertical mode is selected, and the three-dimensionaldisplay is performed by applying the voltage to the respectiveelectrodes;

FIG. 17 is a sectional view of the liquid crystal display device shownin FIG. 14 when the horizontal mode is selected, and the two-dimensionaldisplay is performed without applying the voltage to the respectiveelectrodes; and

FIG. 18 is a sectional view of the liquid crystal display device shownin FIG. 14 when the horizontal mode is selected, and thethree-dimensional display is performed by applying the voltage to therespective electrodes.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIGS. 3, 4 and 5 show a relationship between the liquid crystal and thetransmitted light polarizing direction 40. Referring to FIG. 3, thepolarizing direction 40 is consistent with the longer axis direction ofthe liquid crystal molecule 50. At this time, the liquid crystal worksas a high refractive index medium with respect to the transmitted light.Referring to FIG. 5, the polarizing direction 40 is orthogonal to thelonger axis direction of the liquid crystal molecule 50. Then the liquidcrystal works as a low refractive index medium with respect to thetransmitted light. FIG. 4 represents an intermediate state between thoseshown in FIGS. 3 and 5. Supposing that intensity of the incidentpolarization light is expressed as vector OE, and resolved components ofthe vector OE corresponding to the longer axis direction of the liquidcrystal molecule 50 and corresponding to the direction vertical to thelonger axis direction are designated with OF and OG, the OF passesthrough the high refractive index medium, and the OG propagates in theliquid crystal while passing through the low refractive index medium.The transverse electric field may cause the distribution of therefractive index in the liquid crystal. It is therefore possible to formthe liquid crystal lens 10 under the transverse electric field. Thepresent invention will be described in detail in reference to theexamples.

EXAMPLE 1

FIG. 1 is a sectional view of the liquid crystal display device whichincludes the liquid crystal lens 10 according to Example 1. Referring tothe liquid crystal lens 10 shown in FIG. 1, the liquid crystal isinterposed between the upper substrate 20 and the lower substrate 30.The liquid crystal display panel 100 is provided below the liquidcrystal lens 10. The liquid crystal display panel 100 is illustrated ina simplified manner in FIG. 1, while specifying an arrangement of redsub-pixels r, green sub-pixels g, and blue sub-pixels b. A backlight(not shown) is provided below the liquid crystal display panel 100. Alight ray from the backlight is polarized by the lower polarizer of theliquid crystal display panel 100, modulated by the liquid crystal in theliquid crystal display panel 100, and polarized by the upper polarizerof the liquid crystal display panel 100 again so as to be emitted towardthe liquid crystal lens 10.

The light emitted from the liquid crystal display panel 100 is linearlypolarized in the vertical direction with respect to the plane of thedrawing as the emission polarization direction 40 shows. The liquidcrystal lens 10 acts on the linearly polarized light. FIG. 2 is a planview of the upper substrate 20 of the liquid crystal lens 10 shown inFIG. 1. FIG. 1 is a sectional view taken along line X-X of FIG. 2.Referring to FIGS. 1 and 2, upper substrate electrode patterns 21 arearranged in stripes at predetermined intervals on the upper substrate20.

When the voltage is not applied between the electrodes, the liquidcrystal molecules 50 are aligned in the direction vertical to the planeof the drawing in FIG. 1, that is, in the extending direction of theelectrodes in stripes as shown in FIG. 2. That is, the rubbing directionwhich determines the initial alignment of the liquid crystal lens 10 isconsistent with the extending direction of the electrodes in stripes asshown in FIG. 2. Preferably, the rubbing direction is consistent withthe extending direction of the electrodes in stripes within a range of±5°. In this state, when the polarization light passes through theliquid crystal lens 10, it is expected to pass through the highrefractive index medium because the polarizing direction 40 isconsistent with the longer axis direction of the liquid crystal molecule50. Since the polarization light passes through the uniform medium, thetraveling direction is not changed.

When applying the voltage between the electrodes A and B, the transverseelectric field in parallel with the substrate is generated as shown inFIG. 1 because of no electrodes are formed on the lower substrate 30.The liquid crystal molecules 50 are rotated along the thus generatedelectric field, and aligned as shown in FIG. 1. The light that haspassed through the medium at locations each with a different refractiveindex may be refracted. The polarization light emitted from the liquidcrystal display panel 100 is refracted between the liquid crystalmolecule 50 arranged under the influence of the transverse electricfield and the liquid crystal molecule 50 under no influence of thetransverse electric field.

Referring to FIG. 1, the liquid crystal molecules 50 just above theupper substrate electrode pattern 21 are not influenced by thetransverse electric field, and are not rotated up to the position aroundthe upper substrate 20, thus maintaining the initial alignmentconsistent with the rubbing direction. Meanwhile, the liquid crystalmolecules 50 at an intermediate position between the upper substrateelectrode patterns 21 is influenced most by the transverse electricfield, and the liquid crystal rotates laterally. The thus laterallyrotated liquid crystal molecules 50 act as the low refractive indexmedium with respect to the polarization light in the direction shown inFIG. 1, as described referring to FIGS. 3 to 5.

In the state of the liquid crystal layer where the voltage is applied tothe upper substrate electrode patterns 21, a convex lens 11 as indicatedby a dashed line of FIG. 1 is formed with respect to the polarizationlight shown in FIG. 1. Referring to FIG. 1, the polarization lightsemitted from the sub-pixels of the liquid crystal display panel 100 arecaused to change their paths by an action of the convex lens 11 formedin the liquid crystal lens 10. In other words, the first pixel 200changes the path to the right and the second pixel 300 changes the pathto the left so that the first pixel 200 and the second pixel 300 arerecognized by right and left eyes, respectively. Different signals areinput to the first pixel 200 and the second pixel 300 so as to producethe three-dimensional image.

The AC voltage is applied between the electrodes A and B. An electricforce line 60 has its direction cyclically changed. The direction of theliquid crystal molecule 50 is influenced by the effective value of theelectric field, and accordingly, there is no change in the alignmentdirection of the liquid crystal molecule 50. In the aforementionedexplanation, the electrodes are arranged in stripes on the uppersubstrate 20, and no electrodes are provided on the lower substrate 30.However, it is possible to form the convex lens 11 in the structurehaving the electrodes arranged in stripes on the lower substrate 30 andno electrodes on the upper substrate 20.

In Example 1, each of the first pixel 200 and the second pixel 300includes red sub-pixels r, green sub-pixels g, and blue sub-pixels b.However, colors or the number of the sub-pixels are not limited to theaforementioned structures but may be arbitrarily changed.

EXAMPLE 2

This example provides the liquid crystal display device capable ofselecting the display screen between vertical mode and horizontal modeusing the liquid crystal lens 10. In the liquid crystal lens 10, theelectric field generated by the electrode between the upper substrateelectrode pattern 21 and the lower substrate electrode pattern 31 isdesignated as a longitudinal electric field, and the electric fieldgenerated only by the upper substrate electrode pattern 21 or the lowersubstrate electrode pattern 31 is designated as the transverse electricfield. This example uses the liquid crystal lens 10 formed under thelongitudinal electric field for one of the vertical mode and thehorizontal mode, and the liquid crystal lens 10 formed under thetransverse electric field for the other mode.

FIG. 6 is a plan view which represents the pixel structure in the liquidcrystal display panel 100. Referring to FIG. 6, each of the first pixel200 and the second pixel 300 includes the sub-pixels r, g and b in thelateral direction. The same pixels are arranged in the longitudinaldirection. Each size of short diameter dx and long diameter dy of thesub-pixel may be set to 25 μm and 75 μm respectively, for example. Inthe horizontal mode, the liquid crystal lens 10 covers two pixels ddx inthe lateral direction using the single convex lens 11. In the verticalmode, the single convex lens 11 covers two pixels ddy in thelongitudinal direction. Generally, each dimension of ddx and ddy is thesame. However, those dimensions may be different.

FIG. 7 is a plan view showing the lower substrate electrode patterns 31and the upper substrate electrode pattern 21 according to the example.The lower substrate electrode patterns 31 indicated by the solid line,that is, the electrodes A extend laterally, and are longitudinallyarranged in stripes at predetermined intervals. The lower substrateelectrode pattern 31, that is, the electrode A has a width w1 ofapproximately 10 μm. The interval between the lower substrate electrodepatterns 31, that is, the electrodes A is set to the value correspondingto two pixels as shown in FIG. 6, for example, 150 μm so as to cover theddy shown in FIG. 6.

The upper substrate electrode patterns 21 indicated by the dashed lineshown in FIG. 7 include the narrow electrode B and the wide electrodesD. The distance between centers of the narrow electrodes B is set to thevalue corresponding to two pixels, for example, 150 μm, which covers theddx shown in FIG. 6. An interval d1 between the wide electrode D and thenarrow electrode B is set to approximately 5 μm. The width w3 of thewide electrode D is set to 130 μm, for example.

As described referring to FIG. 6, each of the dimensions ddx and ddy maybe equivalent or different. The interval between the electrodes B on theupper substrate 20, and the interval between the electrodes A on thelower substrate 30 may vary accordingly. The interval between theelectrodes B on the upper substrate covers the ddx, but is notnecessarily consistent with the dimension ddx. On the lower substrate,the interval between the electrodes A covers the ddy, but is notnecessarily consistent with the ddy.

Referring to FIG. 7, the rubbing direction, that is, the initialalignment direction of the liquid crystal molecule 50 is the same as theextending direction of the upper substrate electrode pattern 21. The“same direction” does not necessarily mean “full matching”. There may bethe case where such direction is made slightly different from theextending direction of the upper substrate electrode pattern 21 toprevent occurrence of domain. Preferably, the extending direction of theupper substrate electrode pattern 21 is consistent with that of therubbing direction that determines the initial alignment of the liquidcrystal molecule 50 within a range of ±5°. Referring to FIG. 7, it ispossible to apply different voltages to the electrodes A, B and D,respectively.

FIG. 8 is a sectional view taken along line Y-Y of FIG. 7, whichrepresents the case where the display is used in a horizontal mode.Specifically, FIG. 8 is a sectional view showing alignment of the liquidcrystal molecules 50 when applying the voltage different from thoseapplied to the electrodes B and D to the electrode A as indicated byFIG. 7. Referring to FIG. 8, the polarizing direction 40 of thepolarization light emitted from the liquid crystal display panel 100 isin parallel with the plane of the drawing as indicated by the arrow.Referring to the sectional view taken along line Y-Y, the uppersubstrate electrode patterns 21 are formed as a continuous pattern. Theliquid crystal molecules 50 are aligned under the electric fieldgenerated between the electrodes in stripes as the lower substrateelectrode patterns 31 and the upper substrate electrode patterns 21.

As the polarizing direction of light emitted from the liquid crystaldisplay panel 100 is in parallel with the plane of the drawing, theconvex lens 11 as indicated by the dashed line in FIG. 8 is formed withrespect to the polarization light in the liquid crystal lens 10. Theoperation of the lens is similar to the one described referring to FIG.13. When using the display screen in horizontal mode, the longitudinalelectric field is generated between the upper substrate electrodepatterns 21 and the lower substrate electrode patterns 31 to form theconvex lens 11, thus allowing the three-dimensional image display. Thealignment direction of the liquid crystal molecule 50 when no voltage isapplied between the upper substrate electrode patterns 21 and the lowersubstrate electrode patterns 31 is similar to the case as describedreferring to FIG. 12. In this case, the convex lens 11 is not formed soas to perform the normal two-dimensional image display.

Each of FIGS. 9 and 10 is a sectional view taken along line X-X of FIG.7, which represents the operation when using the display screen invertical mode. Referring to FIGS. 9 and 10, the narrow electrodes B andthe wide electrodes D extend in the vertical direction with respect tothe plane of the drawing on the upper substrate 20. There are noelectrodes arranged on the lower substrate 30. Referring to FIG. 9,since the voltage is not applied between the respective electrodes ofthe liquid crystal lens 10, the liquid crystal molecule 50 is kept inthe initial alignment by rubbing. In this case, the display screen isused for displaying the two-dimensional image.

FIG. 10 is a sectional view which illustrates the operation of theliquid crystal lens 10 when applying voltage different from thoseapplied to the electrodes A and D to the electrode B. Referring to FIG.10, the transverse electric field is generated between the electrodes B,and those of A and D. The transverse electric field rotates the liquidcrystal molecules 50 at the upper electrode side. Then those moleculesare aligned in parallel with the plane of the drawing as FIG. 10 shows.The light emitted from the liquid crystal display panel 100 is polarizedvertically with respect to the plane of the drawing. The aforementionedpolarization light is not influenced by the transverse electric field.In other words, the liquid crystal molecule 50 that is not rotated underthe electric field exhibits a higher refractive index than that of theliquid crystal molecule 50 rotated under the influence of the transverseelectric field. Then the convex lens 11 as shown in FIG. 10 is formed inthe liquid crystal layer.

The first pixel 200 and the second pixel 300 (not shown) are arrangedbetween the electrodes B. The first pixels 200 are recognized by theright eye, and the second pixels 300 are recognized by the left eye soas to form the three-dimensional image. When using the display screen inthe vertical mode, the three-dimensional image is formed by the liquidcrystal lens 10 under the transverse electric field.

When the convex lens 11 is formed under the transverse electric field,the longitudinal electric field is generated between the electrodes Aand B as shown in FIG. 7. The longitudinal electric field may disturbthe lens under the transverse electric field. However, since the areaoverlapped between the electrodes A and B is very small as shown in FIG.7, the influence on the image is limited even if the domain is formed atthat part. Such influence may further be reduced by decreasing the widthof the overlapped part between the electrodes A and B.

The convex lens 11 may be formed to generate the 3-D image if the uppersubstrate electrode patterns 21 and the lower substrate electrodepatterns 31 are arranged on the lower and the upper electrodes in aninverted manner. Selective use of the longitudinal electric field andthe transverse electric field in the liquid crystal lens 10 allowsswitching of the display screen between the vertical mode and thehorizontal mode. This makes it possible to realize the liquid crystaldisplay device capable of selecting the display screen between thevertical mode and the horizontal mode while selectively using thelongitudinal and transverse electric fields in the liquid crystal lens10.

According to Examples 1 and 2, the interval between the upper substrate20 and the lower substrate 30 of the liquid crystal lens 10, that is,the thickness of the liquid crystal layer is equal to or smaller thanhalf the lens diameter of the convex lens 11 to be formed, for example,75 μm or smaller. Meanwhile, if the liquid crystal layer has a largerthickness, the response speed of the liquid crystal lens 10 may bereduced. Preferably, the interval between the upper substrate 20 and thelower substrate 30 for the liquid crystal lens 10 is as small aspossible within the range which substantially allows formation of theconvex lens.

1. A liquid crystal display device having a liquid crystal lens arrangedon a liquid crystal display panel, wherein the liquid crystal displaypanel includes a first pixel that contains a red sub-pixel, a greensub-pixel and a blue sub-pixel, and a second pixel that contains a redsub-pixel, a green sub-pixel and a blue sub-pixel; the liquid crystallens is formed by interposing a liquid crystal between a first substrateand a second substrate; the first substrate has a plurality ofelectrodes in stripes, extending in a first direction, and arranged atpredetermined intervals in a second direction; the second substrate hasno counter electrodes corresponding to the electrodes in stripes; aninitial alignment of liquid crystal molecules between the first andsecond substrates is set to be in the first direction; a differentvoltage is allowed to be applied to each of the electrodes adjacent witheach other among the plurality of electrodes in stripes; and the firstand second pixels of the liquid crystal display panel are contained inthe interval between the adjacent electrodes in stripes.
 2. The liquidcrystal display device according to claim 1, wherein a direction of theinitial alignment of the liquid crystal molecules in the liquid crystallens is consistent with an extending direction of the electrodes instripes within a range of ±5°.
 3. The liquid crystal display deviceaccording to claim 1, wherein the first substrate is positioned at aside opposite the liquid crystal display panel.
 4. A liquid crystaldisplay device having a liquid crystal lens arranged on a liquid crystaldisplay panel, wherein the liquid crystal display panel includes a firstpixel that contains a red sub-pixel, a green sub-pixel and a bluesub-pixel, and a second pixel that contains a red sub-pixel, a greensub-pixel and a blue sub-pixel; the liquid crystal lens is formed byinterposing a liquid crystal between a first substrate and a secondsubstrate; the first substrate has a plurality of electrodes in stripes,extending in a first direction, and arranged at predetermined intervalsin a second direction; the second substrate has no counter electrodescorresponding to the electrodes in stripes; an initial alignment ofliquid crystal molecules between the first and second substrates is setto be in the first direction; a different voltage is allowed to beapplied to each of the electrodes adjacent with each other among theplurality of electrodes in stripes; the first and second pixels of theliquid crystal display panel are contained in the interval between theadjacent electrodes in stripes; application of a different voltage toeach of the adjacent electrodes among the plurality of electrodes instripes allows generation of a three-dimensional image; and applicationof one voltage to each of the adjacent electrodes among the plurality ofelectrodes in stripes allows generation of a two-dimensional image.
 5. Aliquid crystal display device having a liquid crystal lens arranged on aliquid crystal display panel, wherein the liquid crystal display panelincludes pixels each having a red sub-pixel, a green sub-pixel, and ablue sub-pixel arranged in a first direction, which are provided in thefirst direction at first intervals, and further arranged in a seconddirection orthogonal to the first direction at second intervals; theliquid crystal lens is formed by interposing a liquid crystal between afirst substrate and a second substrate; the first substrate includes aplurality of first electrodes in stripes, extending in the firstdirection, and arranged in the second direction each at an intervaltwice as large as the second interval; the second substrate includessecond narrow electrodes in stripes and third wide electrodes instripes, extending in the second direction, and arranged in the firstdirection at predetermined intervals, having the second electrodesarranged in the first direction at the interval as large as the firstinterval; an initial alignment of liquid crystal molecules between thefirst and second substrates is in the first direction; and differentvoltages are allowed to be applied to the first, the second and thirdelectrodes.
 6. The liquid crystal display device according to claim 5,wherein a direction of the initial alignment of the liquid crystalmolecules in the liquid crystal lens is consistent with an extendingdirection of the first electrode within a range of ±5°.
 7. The liquidcrystal display device according to claim 5, wherein the first substrateis positioned at a side of the liquid crystal display panel.
 8. A liquidcrystal display device having a liquid crystal lens arranged on a liquidcrystal display panel, wherein the liquid crystal display panel includespixels each having a red sub-pixel, a green sub-pixel, and a bluesub-pixel arranged in a first direction, which are provided in the firstdirection at first intervals, and further arranged in a second directionorthogonal to the first direction at second intervals; the liquidcrystal lens is formed by interposing a liquid crystal between a firstsubstrate and a second substrate; the first substrate includes aplurality of first electrodes in stripes, extending in the firstdirection, and arranged in the second direction each at an intervaltwice as large as the second interval; the second substrate includessecond narrow electrodes in stripes and third wide electrodes instripes, extending in the second direction, and arranged in the firstdirection at predetermined intervals, having the second electrodesarranged in the first direction at the interval twice as large as thefirst interval; an initial alignment of liquid crystal molecules betweenthe first and second substrates is in the first direction; the secondand third electrodes are set to be at one potential, and a voltage isapplied between the second and first electrodes, and between the thirdand first electrodes to allow a three-dimensional display; and the firstand third electrodes are set to be at the one potential, and the voltageis applied between the first and second electrodes, and between thethird and second electrodes to allow a three-dimensional display.
 9. Theliquid crystal display device according to claim 8, wherein arectangular display screen is provided; the second and third electrodesare set to be at the one potential, and the voltage is applied betweenthe second and first electrodes, and between the third and firstelectrodes to perform the three-dimensional display by selecting thedisplay screen in a horizontal mode; and the first and third electrodesare set to be at the one potential, and the voltage is applied betweenthe first and second electrodes, and between the third and secondelectrodes to perform the three-dimensional display by selecting thedisplay screen in a vertical mode.